Why don't we write configuration files in D instead of JSON?

[Guido via Digitalmars-d-learn]

It would seem that by running the file through mixin, you can 
simply create the vars you want in scope. The drawback being 
random code execution. Is there any way to sanitize mixin code 
from user-configurable file?

Once that's shot down, does anyone know a .json to .sdl converter 
program